1. Field of the Invention
The present invention relates to computer network systems which include mainframe devices and, more particularly, to a method for providing unique names to subordinate resources addressed by the mainframe device.
2. Background Information
The System Network Architecture (SNA) was developed by IBM as a means to interconnect one or more mainframe devices with computer terminals, printers, personal computers, and other devices, denoted as Physical Units (PUs). A PU may include one or more Logical Units (LUs). In the present state of the art, the LUs communicate with the mainframe device in the SNA system by means of IBM's Virtual Telecommunications Access Method (VTAM).
In the SNA system, each PU is assigned a name obtained from a resource definition file resident in the local directory of the mainframe device. The term ‘resource’ is used herein to refer to any network accessible unit (NAU), such as a PU, an LU, or a control point, that can be represented in the local directory. The local directory resource definition file thus contains the logical name, or resource name, and node identification for each NAU in the SNA system. In particular, the TN3270 server utilizes resource names of eight characters in length, in accordance with SNA/VTAM standards, with the requirement that each resource name be unique. By utilizing resource names in the network, an end user can begin a session as an LU without needing to know the locations of the network resources.
There has always been a problem when attempting to derive subordinate resource names from the name of the corresponding superior resource. Currently, there is no scheme by which, when attempting to do such derivation, one can assure that unique subordinate names are generated.
The TN3270 server allows the user/administrator to specify a ‘user seed’ to be used for subordinate resource names. If a user seed is not specified, a name seed is provided by using the first five characters of the PU name. Either seed is then used to create names for the subordinate resources by appending to the seed an index value ranging from 1 to 255.
Such conventional derivation methods for name seeds cause clashes of the subordinate resource names in the name space. By way of example, a clash will most likely result when the first five characters in the PU names remain invariant.
What is needed is a method for deriving subordinate resource names which insures that the derived names are unique.